This invention relates generally to a log skidder and more particularly concerns the adjustability of the fairlead roller which guides the winch cable.
During operation of log skidders that use a winch to drag the log or logs into position rearward of the vehicle and to secure them during transport three problems may arise. The first problem arises during the cable dragging operation when the logs can be either directly behind the vehicle or rearward of the vehicle but offset to either side. This operation under the latter condition requires a lower vertical position of the fairlead roller than that required for the direct rear dragging because the side-tip moment is increased by the angled dragging.
The second dragging problem is caused either by the variances in the sizes of logs that the vehicle may be required to handle or by the variances in the soil conditions upon which the vehicle is required to operate. The larger log diameters and drier terrain require a lower vertical position of the fairlead roller to obtain maximum dragging efficiency, while the small log diameters and swampy soil conditions require a high vertical location of the fairlead roller to obtain the same efficiency in dragging. The third problem arises from varying the horizontal position of the roller with respect to the butt pan surface when the vertical adjustments are made. If this horizontal position varies outside the normally acceptable range, the load being transported may either act as a rudder or adversely affect the load distribution necessary for proper steering.
The existing adjustable fairlead roller systems do not adequately provide solutions to these problems. These systems all require excessive manual handling of the very heavy elements of the logging arch. Two of the systems also produce an unacceptable horizontal position variation with respect to the butt plates. Accordingly, it is the primary aim of the present invention to overcome the problems of prior systems while providing a functional and practical means for adjusting the vertical position of the fairlead roller using the power of a winch to control the heavy elements of the machine.
With more particularity, it is an object of the present invention to provide a fairlead roller adjusting system where the horizontal distance traversed from the low to the high positions is within the normally acceptable range to insure adequate steering.
Similarly, it is an object of the present invention to provide a system which requires a minimum of manual handling of the elements of the machine.
Another object is to provide a method of pivotal adjustment of the vertical location of the fairlead roller which utilizes the power of the vehicle's self-contained power source to relocate the roller.
Finally, it is an object of the present invention to provide a system in which restraints on the adjustable fairlead roller assembly are redundant thereby rendering the adjustment procedure relatively safe to personnel in and around the vehicle.